Metallic boat for use in high temperature furnaces



Jalh 3Q 1.939. G. H. HowE 2,142,846

METALLIC BOAT FOR USE IN HIGH TEMPERATURE FURNACES Original Filed Sept. 1'7, 1937 Invetor:

Goodwin H. Howe,

bg )V H @ttor-neg- Patented Jan. 1939 ZUN'ITED STATES/fi 1 METALLIC noa'rzr'on UsE mman ,y TEMPERATURE FUnNAcEs Goodwin n. Howe, sentia, N. Y.,assigiioi 'ai General Electric Company,` a corporation of New y York I original application september 17, 1937, serial No. 164,354.` Divided and this application Deembelzs, `1931, seriaiNo. 182,087

6 Claims.

The present invention is a division of my copending application Serial No. 164,354, filed September 17, 1937, and entitled Sintered alloy and method for making the same. In` my prior application I have disclosed a furnace and method for fabricating from powdered materials alloys of the type disclosed in Ruder Patents 1,947,274 and 1,968,569, and Mishima Patents 2,027,994 to 2,028,000 inclusive. Alloys of this type, when made from powdered ingredients, are sintered in furnaces which employ a'reducing latmospherasuch as hydrogen, kand operate 'at temperatures in the neighborhood of 1400* C. The sintering chamber 'of such furnaces generally comprises an iron tube supported in an alundum tube which is electrically-heated. In a continuous process for sintering alloys of the Ruder and Mishima type, it is desirable to employ metal `boats on which the various pieces of material to be sintered may be positioned and then pushed through the furnace. Since the atmospheric conditions in the hot zone of the sintering section of the furnace is ideal for causing sticking of the boats to the iron tube, owing to the reducing action of the hydrogen and the high temperature employed, it is necessary `to employ boats which avoid this diiiiculty.

It is an object of the present invention to provide a simple and economical form of metallic boat` which will not stick to the iron .tube portion of the furnace but which will 4permit free movement therethrough at the elevated temperatures.

The novel features which are characteristic of my invention are set forth with particularity in the appended claims. 'I'he invention itself however will best be understood from reference to the following specification when lconsidered in `connection with the accompanying drawing in which Fig. 1 is alongitudinal cross section of a boat employed in carryingout my invention, while Fig. `2 `is a plan view of the boat illustrated in Fig. 1. In fabricating the boat which I have designated as a whole. by the numeral I, substantially pure iron powder is mixed with a smaller quantity of aluminum oxide powder, for example 75% iron andabout` 25% aluminum oxide and spread into a=relatively thin even outer layer. 2 having the surface dimensions; required for the nished part. inner layer 3 of powdered #iron is then superimposed on the first mentionedlayer and the two layers pressed together in a moldand then sintered for about two hours at about `1450 C. Owing to the presence of the iron layer two or A second and thicker more metal pieces thus fabricated may be readilyf, welded together as indicated at 4 and i. to thereby provide boats of any desired `width and. length. End pieces 6 and l having respectively oxide-iron mixtures 8 and `il on the outsidepor- 5 tions thereof `are welded to the flat or `base of the boat as indicated at l in Figs.'1 and 2.

A boat may be constructed entirely ofthe 25% aluminum oxide, 75% iron mixture but such material cannot be welded and unless a large enough 10 i mold is available to press a complete boat it is necessary'to use piecesA of composite` construction havingA a weldable material on I'one side. A further advantage of using a composite boat is that any deformation of the boat due to alternate heating and cooling such as experienced yin the process disclosed in 'applicants prior applicationimay be removed by cold pressing without danger of breakage or oxidation. i l

While I prefer to employ a mixture of `about y 75% iron and 25% aluminum oxide in theconstruction of the boat I these percentages are not critical and may be varied to a considerable extent.v Furthermore, I may, if desired, employ in the constructionk of the boats a mixture of 25 aluminum oxide or any other` inert oxide ,with-` weldable metals other than iron. For example, if unusually highl temperatures are to be employed in the sintering operation, metals such as tungsten, molybdenumand the like may be employed .to replace thek iron in part or if desired the iron may be replaced entirely by molybdenum.

What I claimv asv new and desire to secure by Letters Patent of the United States is:

1. A metal boat adaptedl to carry `material through a furnace, said boat comprising a flat portion consisting of two superimposed layers, the outer layer consisting substantially of a mixture of weldable metal and an inert oxide and the inner layer consisting substantially of weldable metal.

v2.11 metal boat adapted to carry material through a furnace, said boat comprising a flat portionand an end portion, each of said portions consisting of two superimposed layers of 45,

material, the outer layer of said fiat portion and the outer layer of said end portion consisting substantially of Va mixture of a weldable metal and an inertv oxide, and the inner layer of 'said flat through `a. furnace, said boat `comprising two superimposed layers, the outer layer consisting of a mixture of iron and aluminum oxide and the inner las-'er consisting substantially 4of iron. num oxide und each. inner loyer consisting lub- 4. A"meta.l. boatl adapted to carry material 'throug'lia.iurnoce,said 'bostcomprising two A v superimposedA lajyerm*l the outer .tlayerj` consisting `of '15% ironlnnd'25% valuminumoxide, `and the portion and a vertical portion substantially at' right angles thereto. each of said Aportionsvcox'isisting oi' two superimposed layers, each outer. loyerl consisting `oi a mixture of iron and slumit 6. A meta1"boat odspted'to carry materiel through a furnace. ssid'bost comprising s not portion end a vertical portion substantially at right angles thereto, `eatch oi said portions consisting of two superimposed layers, eachouter layer consisting of a mixture of about 75% iron.

vand 25% aluminum oxide', snd'each inner` loyer consisting substantially of iron.

ooonwmin `Howiiz. 

